VWF and open-angle glaucoma: Similarly, the plasma levels of VEGF and the von Willebrand factor (vWf) were significantly elevated in patients with NTG and POAG compared to healthy controls, while the concentration of the soluble receptor for VEGF (sFlt-1) was significantly lower in the glaucomatous groups, which may be associated with abnormal vascular permeability and endothelial damage/dysfunction [179].